It is well known in the art that aerosol packages deliver optimum performance for hair sprays and other personal care formulations. However, because of environmental considerations, use of such packages will be minimized in the near future. Pump dispensers are acceptable alternatives to aerosols, providing that alcohol is used as a solvent of these formulations to minimize the tendency to clog. Nevertheless, alcohol is a volatile organic compound (VOC) and such compounds also create environmental damage. Future VOC standards will limit the use of VOCs.
The obvious substitute for VOCs is water. Nevertheless, water based formulations cause known types of pump dispensers to clog, particularly when the formulations contain high percentages of solids.
The copending application discloses a new and improved type of atomizing pump dispenser which is capable of properly delivering water based formulations without clogging even when such formulations contain high percentages of solids. The various components of this dispenser whether moved together or apart or maintained in continuous sliding contact during operation are subjected to a self cleaning or wiping action which prevents buildup onto these parts of solids in the formulation. In some applications, however, the discharge orifice can become obstructed, causing the dispenser to fail.
The present invention is directed toward a new and different pump dispenser, termed an air purge pump dispenser, which delivers water based products without clogging by introducing air into the discharge spray at some point during actuation, followed by an air purging action which removes the remnants of the product from the spray path before such remnants come in contact with the oxygen in the air, solidify and obstruct the discharge orifice.